The present invention relates to an image transfer sheet capable of image transfer without substantial application of heat, a method for making the image transfer sheet, and a method for transferring an image to a substrate from an image transfer sheet, without a substantial addition of heat.
Image transfer to articles made from materials such as fabric, nylon, plastics and the like has increased in popularity over the past decade due to innovations in image development. On Feb. 5, 1974, La Perre issued a United States patent describing a transfer sheet material markable with uniform indicia and applicable to book covers. This sheet material included adhered plies for an ink-receptive printable layer and a solvent-free, heat-activatable adhesive layer. The adhesive layer was somewhat tacky prior to heat activation to facilitate positioning of a composite sheet material on a substrate which was to be bonded. The printable layer had a thickness of 10-500 microns and had an exposed porous surface of thermoplastic polymeric material at least 10 microns thick.
Indicia were applied to the printable layer with an old typewriter. A thin film of temperature-resistant, low surface energy polymer, such as polytetrafluoroethylene surface and heated with an iron. Heating caused the polymer in the printable layer to fuse, thereby sealing the indicia into the printable layer.
On Sep. 23, 1980, Hare had issued U.S. Pat. No. 4,224,358 described a kit for applying a colored emblem to a t-shirt. The kit comprised a transfer sheet which included the outline of a mirror image of a message. To utilize the kit, a user applied a colored crayon to the transfer sheet and positioned the transfer sheet on a T-shirt. A heated instrument was applied to the reverse side of the transfer sheet in order to transfer the colored message.
The Greenman et al. patent, U.S. Pat. No. 4,235,657, issuing Nov. 25, 1980, described a transfer web for a hot melt transfer of graphic patterns onto natural, synthetic fabrics. The transfer web included a flexible substrate coated with a first polymer film layer and a second polymer film layer. The first polymer film layer was made with a vinyl resin and a polyethylene wax which were blended together in a solvent or liquid solution. The first film layer served as a releasable, separable layer during heat transfer. The second polymeric film layer was an inonomer in an aqueous dispersion. An ink composition was applied to a top surface of the second film layer. Application of heat released the first film layer from the substrate while activating the adhesive property of the second film layer, thereby transferring the printed pattern and a major part of the first layer along with the second film layer onto a work piece. The second film layer bonded the printed pattern to the work piece while serving as a protective layer for the pattern.
The Sanders et al. patent, U.S. Pat. No. 4,399,209, issuing Aug. 16, 1983, and describes an imaging system in which images were formed by exposing a photosensitive encapsulate to actinic radiation and rupturing the capsules in the presence of a developer so that there was a pattern reaction of a chromogenic material present in the encapsulate or co-deposited on a support with the encapsulate and the developer which yielded an image.
The Goffi patent, U.S. Pat. No. 4,880,678, issuing Nov. 14, 1989, describes a dry transfer sheet that comprises a colored film adhering to a backing sheet with an interposition of a layer of release varnish. The colored film included 30-40% pigment, 1-4% of cycloaliphatic epoxy resin, from 15-35% of vinyl copolymer, from 1-4% of polyethylene wax. This particular printing process was described as being suitable for transferring an image to a panel of wood.
The Kronzer et al. patent, U.S. Pat. No. 5,271,990, issuing Dec. 21, 1993, describes an image-receptive heat transfer paper that included a flexible paper-based web sheet and an image-receptive melt transfer film that overlaid a top surface of the base sheet. The image-receptive melt transfer film was comprised of a thermoplastic polymer melting at a temperature within a range of 65-180xc2x0 C.
The Higashiyami et al. patent, U.S. Pat. No. 5,019,475, issuing May 28, 1991, describes a recording medium that included a base sheet, a thermoplastic resin layer formed on at least one side of the base sheet and a color developer layer formed on a thermoplastic resin layer and capable of color development by reacting with a dye precursor.